Originally posted by vanquish:[..]
They have this sort of dark stain on them, it looks like an oil stain but it's dry.
I don't know what it is, but I want to remove it without rubbing off the gold plating.
Oh yes, if it is dry you should remove it, it won't do any good (and looks very bad for sure)... A soft damp coth and a bit of soap (or any grease/oil remover) will do it.